This invention relates to a fiber optic device for the transmission and lateral irradiation of laser energy, particularly for angioplasty.
Angioplasty is used in the medical field for removing arteriosclerotic plaques and similar obstructions which form in the arteries, in particular the coronary arteries.
Angioplasty is currently effected by various methods, some of which involve operating from within the artery itself.
One of these known methods comprises the use of a catheter provided at its end with a small inflatable ball. The catheter with the deflated ball is inserted into the artery and advanced until the ball reaches the obstacle to be removed. The ball is then inflated and as i expands, it recanalizes the obstructed vessel. This method has serious drawbacks (see Nigel Sinclair et al, S.P.I.E., vol. 713, page 70, September 1986). In particular, rather than remove the obstruction, this method tends to widen the artery at that particular location. This means that the beneficial effects are only temporary, as the obstruction forms again after a short time.
For these reasons particular attention has been given to laser techniques, which, because of the high energy concerned, are able to destroy and thus definitively eliminate arteriosclerotic plaques.
A known technique is to insert into the artery an optical fiber with a sapphire tip, which emits a laser beam able to destroy the arteriosclerotic plaque facing it.
Drawbacks of this known technique include on the one hand the large size of the sapphire tip, which means that the apparatus can be used only for peripheral large-diameter blood vessels, and on the other hand the risk of perforating the artery wall should this face the laser beam emitted from the sapphire tips as from any conventional fiber tip.
To obviate these drawbacks it has been proposed to use a fiber optic probe with the laser outlet covered by a metal tip. The tip is heated by the laser beam and is moved forward so that it burns the arteriosclerotic plaque.
The main drawback of this technique is the loss of the potential advantages of the laser source, which in this case is used only to heat the metal tip as in the case of a normal source of electricity, so losing the selective effect of the laser beam on the arteriosclerotic plaque relative to the surrounding healthy tissue.
A further drawback is that the hot tip can adhere to the tissue with the risk of damage.